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## anonymous one year ago Can someone help me on a few questions?

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1. Baby_Bear69

I can try. What are they?

2. anonymous

there is two questions that say evaluate. I have to upload the image though

3. anonymous

4. Baby_Bear69

oh lawd, I seen this in my textbook this year but I haven't learnt it yet, sorry :/

5. anonymous

oh okay well thanks for looking at it :/

6. Nnesha

what is the question ? like what we have to do with that ?

7. anonymous

I have no clue on how to do the question. It just say evaluate then the image i posted.

8. Nnesha

|dw:1439566610288:dw|

9. Nnesha

|dw:1439566827777:dw| there are total 7 term start from 1 a number which is raising to the power is ration

10. Nnesha

so replace n by 2 to find 2nd term 3 to find 3rd term untill 7

11. Nnesha

|dw:1439566934306:dw|

12. Nnesha

we just need that circle part n= terms that you have to find starting from 1 to 7 here i plugin 2 to find 2nd term $\huge\rm 2(-2)^{\color{red}{2}-1}$ like this now solve

13. anonymous

would it be -4?

14. Nnesha

yes right !

15. anonymous

so i just keep plugging number in till i get to 7? Or could i just skip to 7?

16. Nnesha

wait a sec let me solve it first been a year haven't done question like this :/

17. Nnesha

you have to find all terms then add them.

18. Nnesha

we have to evaluate if it say find sum then we can use the formula.

19. dinamix

Nnesha its not function like power series right ?

20. Nnesha

wait doesn't matter you will get the same answer no need to find all terms

21. dinamix

its just total numbers i think

22. Nnesha

$\huge\rm S_n = \frac{ a_1(1-r^n )}{ 1-r }$ use this formula plug in the r and n values then sovle

23. Nnesha

a_1= first term r= ratio n= number of total terms!

24. Nnesha

yeah sum of all 7 terms but we can use that formula to find sum of 7 terms that way we don't have to find 3,4,5,6,7 terms

25. anonymous

so i could do it either way and get the same answer?

26. Nnesha

yes right

27. anonymous

okay thank you!!

28. Nnesha

my pleasure!

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